(a) Field of the Invention
The present invention relates to a method for promoting weight gain in domestic farm animals which comprises subcutaneously implanting a slow-release implant which contains norgestomet in a quantity such that from about 75 to 200 mcg/day is administered for a period of from about 60 to 210 days. In a particular aspect of the invention the slow-release implant is a silastic type implant.
It has long been important to attempt to increase the weight of domestic farm animals eventually sold for consumption. A great deal has been done with chickens, lambs, heifers, etc. and the use of steroids, see e.g., Sci. Agron. Rennes, pg. 74-87 (1981). A number of different anabolic steroids are already commercially useful in producing this effect.
Norgestomet, a progestin, has the structure: ##STR1##
It is useful in controlling estrus and initiating the onset of puberty in female domestic farm animals when administered through a silastic implant for a period of from about 6 to about 21 days in doses of about 100-200 mcg/day.
(b) Information Disclosure
U.S. Pat. Nos. 3,992,518 and 3,946,106 describe microsealed delivery devices (silastic) and methods for making the same which are useful in the practice of this invention. U.S. Pat. No. 3,527,778 describes certain 11-lower alkyl steroids, in particular 17.zeta.-acetoxy-11.beta.-methyl-19-nerpregn-4-ene-3,20 dione or norgestomet. U.S. Pat. No. 3,941,880 describes the use of norgestomet for controlling estrus in female bovines. U.S. Pat. No. 3,860,701 describes a hydron drug delivery system useful in the practice of the invention. U.S. Pat. No. 3,892,855 describes another method of using norgestomet in controlling estrus in female bovines.